Two-Pole Band-pass Filter Based on All-pass Filter

This paper proposes the new two-pole band-pass filter design principle for the all-pass filter and notch filter by applying the least square. The first step is to design notch filter by using pole-zero placement and then modify pole positions to control pass-band filter gain to ensure the symmetry with the maximum gain at the target level. After that, there is the design of all-pass filter with pole at the same positions as the notch filters to make the negative cascade with the designed notch filter to get the transfer function with band-pass filter magnitude response. The results from the experiments on MATLAB have shown the two-pole band-pass filter of the new design with the accurate and symmetric gain.